Multi-axis piezoresistive force sensor

Abstract

A microelectromechanical system (MEMS) sensor device comprising at least one microelectromechanical system sensor to characterize intracellular dynamics and behavior of a living biological cell so as to quantitatively measure the mechanical strength thereof. The microelectromechanical system sensor being responsive to mechanical force changes during said cell's contraction, migration, proliferation and differentiation.

The invention claimed is: 
     
       1. A microelectromechanical system (MEMS) sensor device comprising: a microelectromechanical system sensor to characterize intracellular dynamics and behavior of a living biological cell so as to quantitatively measure a mechanical stiffness and a strength thereof, said microelectromechanical system sensor responsive to mechanical force changes during said living biological cell's contraction, migration, proliferation and differentiation;
 said microelectromechanical system (MEMS) sensor comprising an interaction platform in a form of a mechano-sensitive platform configured to have direct contact with said living biological cell and to measure forces generated by said living biological cell by way of measuring displacements of said interaction platform, wherein said interaction platform is a rectangular planar surface medium, an edge of which is connected with at least two strain-sensitive nanoscale elements in the form of piezoresistive nanowires, wherein said interaction platform is suspended by retaining springs extending between the edge of the interaction platform and a respective anchor associated with said edge; and, 
 said microelectromechanical system (MEMS) sensor comprises strain-sensitive nanoscale elements in a form of electromechanical transducer elements configured to sense mechanical force applied by said cell in direct contact with said mechano-sensitive platform. 
 
     
     
       2. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein said at least two strain-sensitive nanoscale elements connected with the edge of the interaction platform are connected to each other through a conductive edge line at least partially extending along said edge. 
     
     
       3. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein said at least two strain-sensitive nanoscale elements connected with the edge of said interaction platform extend between the interaction platform and a respective anchor associated with said edge. 
     
     
       4. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein said strain-sensitive nanoscale elements are made of doped single crystal silicon. 
     
     
       5. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein said retaining springs are configured such that a stiffness in an out-of-plane bending direction of said interaction platform is higher than that in an in-plane direction whereby the motion of the interaction platform is constrained to in-plane displacements. 
     
     
       6. A microelectromechanical system (MEMS) sensor device as set forth in  claim 5 , wherein a width of said retaining springs is configured in a decreased manner so as to obtain a lower in plane stiffness of said retaining springs and an increased magnitude of strain on the strain-sensitive nanoscale elements. 
     
     
       7. A microelectromechanical system (MEMS) sensor device as set forth in  claim 5 , wherein a height to width ratio of the retaining springs is at least greater than 2 and is preferably between 5 and 15. 
     
     
       8. A microelectromechanical system (MEMS) sensor device comprising: a microelectromechanical system sensor to characterize intracellular dynamics and behavior of a living biological cell so as to quantitatively measure a mechanical stiffness and a strength thereof, said microelectromechanical system sensor responsive to mechanical force changes during said living biological cell's contraction, migration, proliferation and differentiation;
 said microelectromechanical system (MEMS) sensor comprising an interaction platform in a form of a mechano-sensitive platform configured to have direct contact with said living biological cell and to measure forces generated by said living biological cell by way of measuring displacements of said interaction platform and, 
 said microelectromechanical system (MEMS) sensor comprises strain-sensitive nanoscale elements in a form of electromechanical transducer elements configured to sense mechanical force applied by said cell in direct contact with said mechano-sensitive platform and, wherein electric current flowing through a strain-sensitive nanoscale element is measured to proportionally calculate in-plane force gradients being exerted parallel to the surface of said interaction platform. 
 
     
     
       9. A microelectromechanical system (MEMS) sensor device as set forth in  claim 8 , wherein a change in resistance of the strain-sensitive nanoscale element is monitored by current—voltage measurements to determine a relative change in resistance of the strain-sensitive nanoscale element and a magnitude of the force applied by a living biological cell. 
     
     
       10. A microelectromechanical system (MEMS) sensor device as set forth in  claim 9 , wherein the current flowing through the strain-sensitive nanoscale element is monitored while constant voltage is applied. 
     
     
       11. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein a direction of the applied force is determined from a ratio of the strains on strain-sensitive nanoscale elements whose longitudinal axes are perpendicular to each other. 
     
     
       12. A microelectromechanical system (MEMS) sensor device as set forth in  claim 4 , wherein the strain-sensitive nanoscale elements are oriented along directions of a plane of single crystal silicon and are doped with Boron atoms. 
     
     
       13. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein the retaining springs are provided with a folded structure disposed between two linear spring portions. 
     
     
       14. A microelectromechanical system (MEMS) sensor device as set forth in  claim 13 , wherein the folded structure disposed between two aligned spring portions comprises at least two folding lines between two linear spring portions. 
     
     
       15. A microelectromechanical system (MEMS) sensor device as set forth in  claim 13 , wherein the two linear spring portions are disposed at both ends of the folded structure and extend in an aligned manner. 
     
     
       16. A microelectromechanical system (MEMS) sensor device as set forth in  claim 1 , wherein the microelectromechanical system (MEMS) sensor device comprises an array of microelectromechanical system (MEMS) sensors to generate a 2D force vector map to conduct array type parallel time-domain multiplex analysis. 
     
     
       17. A microelectromechanical system (MEMS) sensor device comprising: a microelectromechanical system sensor to characterize intracellular dynamics and behavior of a living biological cell so as to quantitatively measure a mechanical stiffness and a strength thereof, said microelectromechanical system sensor responsive to mechanical force changes during said living biological cell's contraction, migration, proliferation and differentiation;
 said microelectromechanical system (MEMS) sensor comprising an interaction platform in a form of a mechano-sensitive platform configured to have direct contact with said living biological cell and to measure forces generated by said living biological cell by way of measuring displacements of said interaction platform, wherein said interaction platform is suspended by retaining springs extending between the edge of the interaction platform and a respective anchor associated with said edge; and 
 said microelectromechanical system (MEMS) sensor comprises strain-sensitive nanoscale elements in a form of electromechanical transducer elements configured to sense mechanical force applied by said cell in direct contact with said mechano-sensitive platform.